Stereospecific Synthesis of α-Amino Allylsilane Derivatives through a [3,3]-Allyl Cyanate Rearrangement. Mild Formation of Functionalized Disiloxanes

An efficient asymmetric synthesis of alpha-amino allylsilane derivatives is reported. The strategy is based on a [3,3]allyl cyanate sigmatropic rearrangement from enantioenriched gamma-hydroxy alkenylsilyl compounds. The isocyanate intermediate can be trapped by several nucleophiles, opening the way for the preparation of unknown chiral functionalized compounds such as the alpha-ureido allylsilanes as well as carbamate derivatives. A computational study was conducted to rationalize the complete 1,3-chirality transfer of this kind of rearrangement. Moreover, starting from products bearing a phenyldimethyl silyl substituent, the alpha-amino silane derivatives or the corresponding disiloxanes can be obtained under hydrogenation conditions in an exclusive way according to the used catalyst.